University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden


Midseason Yard & Garden Update

July 16, 1998

Rain, humidity, and heat have been the story over the past few weeks. Yard and garden problems have been showing up as a result of the weather.

For example, slime molds have been appearing on mulches. Grayish, green, yellow, whitish, or even purple greasy looking masses describes slime molds. These are actually primitive organisms that slowly move over mulches, sidewalks, and vegetation. Crusty fruiting bodies full of dusty spores will then develop. Other than looking disgusting, slime molds feed on decaying organic matter and are not considered a threat to plants.

As conditions dry out, the slime molds will disappear. Rake or brush them away. Periodically raking or fluffing mulch may help reduce the problem.

Another problem related to the weather and very visible in lawns is crabgrass. Rapidly growing patches of light green, weedy-looking grass in the lawn is most likely crabgrass. Unfortunately, there is little that can be done with existing plants. If numbers are low, pull them out by hand. Postemergence crabgrass herbicides work best on very small plants, so it may be too late for them to be effective. Remember crabgrass is an annual that dies off in early fall.

Leaf diseases on tomatoes have been favored by the warm, humid weather. Brown spots on lower leaves could be either early blight or Septoria, both caused by fungi. When they first appear, remove infected leaves and any leaves fallen to the ground. Try to keep moisture off the leaves when watering. If using a sprinkler, water early in the day so leaves dry quickly.

Foliage not yet infected with early blight or Septoria can be also be protected using fungicides. Fungicides containing either maneb or mancozeb will help control both diseases. Look at the active ingredient on the product label for either of these fungicides. Read and follow all label directions.

As with many other diseases, sanitation can help prevent future problems. Remove infected plants as soon as possible. At the end of the season, remove all plant material from planting areas. Rotate vegetable crops in 1999 to help prevent diseases.


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